Japanese Patent Laying-Open No. 2005-57931 discloses a stator using an edgewise coil. In this stator, an insulating bobbin having an edgewise coil wound around includes a teeth insulating part insulating a tooth from the edgewise coil and first and second extending parts each extending from each end portion of the teeth insulating part approximately parallel to a yoke inner surface.
In the stator disclosed in the above publication, the first and second extending parts are each provided at each end portion of the teeth insulating part. Therefore, in order to form an edgewise coil, it is necessary to wind a flat wire around the insulating bobbin. The edgewise coil, however, requires bending in the width direction of the flat wire, and it is therefore not always easy to form the edgewise coil by winding a flat wire around the insulating bobbin. Moreover, in the aforementioned stator, the rigidity of the insulating bobbin has to be increased because a great force is exerted on the insulating bobbin during coil winding. As a result, the insulating bobbin is unfortunately increased in size.